Foveal metacontrast: I. Criterion content and practice effects.

Ventura, Joel

doi:10.1037/0096-1523.6.3.473

Cited by 26 publications

(42 citation statements)

References 32 publications

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“…Psychophysical data, however, show metacontrast to be more complex than either the models and theories cited above or the electrophysiological correlates would imply. An effect that none of the present models can explain with their proposed neural interactions is the near disappearance of metacontrast with enough practice (Ventura, 1980). Vttal (1971) gives other, more general reasons why current neurophysiological models are unsatisfactory.…”

Section: Discussionmentioning

confidence: 99%

“…A recent paper on electrophysiological correlates of metacontrast showed no YEP correlates of metacontrast in a "C1" component that reflected activity of striate cortex (Jeffreys & Musselwhite, 1986). However, while C1 is an early potential that reflects afferent activity, extensive evidence, much of it published in Perception & Psychophysics, has shown metacontrast to be a complex phenomenon that is influenced by repetition, practice, binocularity, and other effects to be expected at a higher level (Schiller & Greenfield, 1969;Schiller & Smith, 1968;Ventura, 1980;Weisstein, 1971). Thus, we would expect correlates of metacontrast in laterVEP components, where higher level influences can be seen.…”

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Visual evoked potentials: Concomitants of metacontrast in late components

Bridgeman

1988

Perception & Psychophysics

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Metacontrast is the masking of a briefly flashed target by a subsequent mask that shares common or nearby contours with the target. It is of interest because the effect seems to work backward in time, with a later mask obscuring an earlier target. The delay in masking suggests that the internal representation of a stimulus (the target) remains vulnerable for a time to interference in the nervous system. Thus, metacontrast provides a psychophysical tool for the dissection of temporal aspects of visual coding.In addition to psychophysical studies, the visual evoked potential (YEP) is a source of information used to differentiate the metacontrast theories currently proposed. The YEP has shown promise in revealing where and when in the brain metacontrast interactions occur. A recent paper on electrophysiological correlates of metacontrast showed no YEP correlates of metacontrast in a "C1" component that reflected activity of striate cortex (Jeffreys & Musselwhite, 1986). However, while C1 is an early potential that reflects afferent activity, extensive evidence, much of it published in Perception & Psychophysics, has shown metacontrast to be a complex phenomenon that is influenced by repetition, practice, binocularity, and other effects to be expected at a higher level (Schiller & Greenfield, 1969;Schiller & Smith, 1968;Ventura, 1980;Weisstein, 1971). Thus, we would expect correlates of metacontrast in laterVEP components, where higher level influences can be seen. This paper will show that although correlates of metacontrast are indeed present in the Jeffreys and Musselwhite data, they occur in later components, where other studies would lead us to expect them.Several studies have found a suppression of later components in the YEP that matches psychophysical U-shaped metacontrast functions, even while early components are unaffected (Andreassi, DeSimone, & Mellers, 1975;Vaughan & Silverstein, 1968). Jeffreys and Musselwhite (1986) added to this literature by using electrode placements and stimulus locations that isolated responses of either striate or extrastriate visual cortex (Jeffreys, 1971;Jeffreys & Axford, 1972); the components are termed C1 and C2, respectively. The method is based on the differ- Using this technique, Jeffreys and Musselwhite (1986) reported "no discernible modification of either of the two initial YEP components C1 and C2" (po 631) under stimulus conditions in which they found U-shaped metacontrast masking functions psychophysically. Indeed, their early, prominent C1 and C2 components showed no changes with metacontrast. However, they did not analyze the later components of their VEPs, where others have found correlations with psychophysical metacontrast functions. Because the C1 and C2 potentials are more precisely localized than those in previous studies of metacontrast-related potentials, it is useful to extend the search for YEP correlates of metacontrast to the later components in this study. This paper will show that metacontrast-relatedcomponents do exist in Jeffreys and Musselwhite'...

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Visual evoked potentials: Concomitants of metacontrast in late components

Bridgeman

1988

Perception & Psychophysics

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“…Nonetheless, dealing with an unusual finding such as below-chance performance calls for caution. Nonmonotone masking functions might not reflect nonmonotone changes in sensitivity, and it is possible that sufficient practice might eliminate the masking (Bernstein, Proctor, Proctor, & Schurman, 1973;Hogben & Di Lollo, 1984;Schwiedrzik, Singer, & Melloni, 2009;Ventura, 1980;Wolford, Marchak, & Hughes, 1988). We used extensive training to eliminate practice effects and a rating procedure to estimate each observer's sensitivity as measured by his ROC.…”

Section: Experiments 2: Foveal and Parafoveal Sensitivity (D′)mentioning

confidence: 99%

Nonmonotone backward masking functions and brightness reversals

Stewart

Purcell

Pinkham

2011

Atten Percept Psychophys

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Increasing the target-field luminance aids detection for a simultaneously presented black target disc and a black masking annulus. At an intermediate interval separating the onset of the target from the mask, increasing the target-field luminance reduces target detection. This decrease in performance occurs with both temporal and spatial forced choice tasks. With a spatial forced choice, an observer's performance can fall below chance. We associate below-chance performance with a brightness reversal of the black target disc, such that the target disc appears brighter than its surround. The occurrence of brightness reversals follows from our model of the Broca-Sulzer effect, and nonmonotone masking functions result from a generalization of luminance summation.Keywords Visual backward masking . U-shaped functions . Broca-Sulzer effect . Brightness reversal . Metacontrast maskingThe detection of a briefly flashed target, such as a black disc, is sometimes suppressed by the onset of a second stimulus, the masking stimulus. When the target is followed by a surrounding figure, such as a black annulus, the interplay of target and mask is called backward masking. Under conditions of backward masking, both target detection and letter identification can decrease as the delay between the onset of the stimulus and the onset of the mask increases. The resulting nonmonotone performance curves are addressed by most accounts of visual masking . Under some conditions, however, target detection is worse than chance. No current explanation of masking accounts for below-chance performance.Our account of below-chance performance rests on three propositions: (i) A spatial two-alternative forced choice (2AFC) task can produce nonmonotone performance curves. For pronounced nonmonotone curves, detection can be worse than chance. (ii) These nonmonotone backward-masking curves represent a change in an observer's sensitivity for certain delays between target and mask onset, even for targets that fall on the fovea. A dark target, followed by an appropriate masking stimulus, sometimes appears to be brighter than its background, a phenomenon we have called a brightness reversal . Pronounced brightness reversals occur with black-on-white figures and can lead to below-chance target detection. (iii) Our conjecture is that brightness reversals result from the same combination of excitation, inhibition, and luminance summation that produces the Broca-Sulzer effect (Berman & Stewart, 1978a, 1978b, 1979Marks, 1974). These brightness reversals result in below-chance performance with a spatial 2AFC.

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“…Ventura (1980) found that severity of metacontrast masking decreased dramatically over successive experimental sessions. In view of this result, the question arises as to whether perception of the first stimulus improves with practice in an apparent motion paradigm as well in metacontrast.…”

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Practice reduces suppression in metacontrast and in apparent motion

Hogben

Lollo

1984

Perception & Psychophysics

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A target display consisting of eight dots drawn randomly from a nine-dot square matrix was displayed for 10 msec and was followed, after intervals ranging from 0 to 160 msec, by either two flanking matrices (metacontrast condition) or one flanking matrix (apparent-motion condition). Observers were required to name the location of the missing dot within the target matrix. Identical U-shaped functions of perceptual suppression of the target matrix were obtained in both paradigms. In both cases, level of suppression decreased rapidly with practice so that performance became virtually unimpaired after five testing sessions. The basis of the practice effects was examined in Experiment 2 and was shown to reflect changes in criterion content. 441Perception of a brief visual target is impaired if a second stimulus (a mask) is displayed nearby and soon after. In a classic investigation of this effectknown as metacontrast masking-Alpern (1953) employed a rectangular target followed by a pair of rectangles, one to each side. When the stimulus-onset asynchrony (SOA) between target and mask was either very brief or very long, the target was perceived clearly and accurately. At intermediate SOAs, however, perception of the target was impaired. The same effect is obtained if the mask surrounds the target completely, rather than merely flanking it (e.g., Werner, 1935).Almost invariably, metacontrast masking effects are accompanied by an impression of motion between successive parts of the display. This correlative observation has prompted the conjecture that metacontrast and apparent motion effects may be causally related (Breitmeyer, Love, & Wepman, 1974;Kahneman, 1967). The relationship between the two phenomena was asserted most clearly by Kahneman (1967), who demonstrated the similarity of their temporal requirements. Kahneman (1967) employed a square target followed in time by either two flanking squares (metacontrast paradigm) or only one flanking square (apparent motion paradigm). He found that severity of masking and quality of apparent motion followed identical time courses. Kahneman (1967) also noted that the appearance of the first stimulus was degraded, not only in the metacontrast

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Foveal metacontrast: I. Criterion content and practice effects.

Cited by 26 publications

References 32 publications

Visual evoked potentials: Concomitants of metacontrast in late components

Visual evoked potentials: Concomitants of metacontrast in late components

Nonmonotone backward masking functions and brightness reversals

Practice reduces suppression in metacontrast and in apparent motion

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